Imaging Features of Primary Sclerosing Cholangitis: From Diagnosis to Liver Transplant Follow-up.

Primary sclerosing cholangitis (PSC) is a chronic progressive inflammatory disease of the bile ducts that leads to multifocal bile duct fibrosis, strictures, cholestasis, liver parenchymal changes, and ultimately cirrhosis. It more commonly occurs in young adults, with a variety of clinical and imaging manifestations. The cause of the disease is not known, but it has a strong association with inflammatory bowel disease and can overlap with other autoimmune diseases, including autoimmune hepatitis and immunoglobulin G4-related disease. Patients are predisposed to various hepatic and extrahepatic deteriorating complications, such as bile duct and gallbladder calculi, acute bacterial cholangitis, liver abscess, and portal hypertension, as well as malignancies including cholangiocarcinoma (CCA), gallbladder cancer, and colorectal carcinoma. Imaging has an essential role in diagnosis, surveillance, and detection of complications. MR cholangiopancreatography and endoscopic retrograde cholangiopancreatography have high specificity and sensitivity for detection of primary disease and assessment of disease progression. However, many patients with PSC are still diagnosed incidentally at US or CT. Novel imaging techniques such as transient elastography and MR elastography are used to survey the grade of liver fibrosis. Annual cancer surveillance is necessary in all PSC patients to screen for CCA and gallbladder cancer. Familiarity with PSC pathogenesis and imaging features across various classic imaging modalities and novel imaging techniques can aid in correct imaging diagnosis and guide appropriate management. The imaging features of the biliary system and liver parenchyma in PSC across various imaging modalities are reviewed. Imaging characteristics of the differential diagnosis of PSC, clinical associations, and complications are described. Finally, the role of imaging in evaluation of PSC progression, pre-liver transplant assessment, and post-liver transplant disease recurrence are discussed.© RSNA, 2019.